Waves and Sound Concepts
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Questions and Answers

Which statement about the wave is false?

  • The frequency of the wave is 0.10 Hz.
  • The amplitude is 1.0 m. (correct)
  • The wave is traveling in the negative x direction.
  • The wavelength of this wave is 2.0 m.

Which equation best represents the wave described with an amplitude of 0.35 m, frequency of 1.05 × 10^6 Hz, and speed of light?

  • y = 0.35 sin (6.60 × 10^6t − 0.022x) (correct)
  • y = 0.35 sin (6.60 × 10^6t + 0.022x)
  • y = 0.35 sin (286t + 1.05 × 10^6x)
  • y = 0.35 sin (1.05 × 10^6t + 3.00 × 10^8x)

When a sound wave travels from air into water, how does its wavelength change?

  • The wavelength initially increases and then decreases.
  • The wavelength increases.
  • The wavelength remains the same.
  • The wavelength decreases. (correct)

What type of sound wave is produced by a loudspeaker?

<p>Longitudinal wave (C)</p> Signup and view all the answers

Which frequency range is considered ultrasonic?

<p>Above 20 kHz (D)</p> Signup and view all the answers

What quality does the brain interpret from a detected frequency in terms of sound?

<p>Pitch (B)</p> Signup and view all the answers

What describes the direction of disturbance in a transverse wave?

<p>Disturbance occurs perpendicular to wave travel. (B)</p> Signup and view all the answers

The change in pressure amplitude relates to which quality of sound?

<p>Loudness (A)</p> Signup and view all the answers

What is the maximum excursion of a particle from its undisturbed position in a wave referred to as?

<p>Amplitude (C)</p> Signup and view all the answers

Which type of tone is produced by a sound wave with a single frequency?

<p>Pure tone (D)</p> Signup and view all the answers

Which of the following correctly describes frequency in the context of waves?

<p>Frequency is the number of wave cycles per second. (D)</p> Signup and view all the answers

What is the relationship between the speed, wavelength, and frequency of a wave expressed as?

<p>v = fλ (C)</p> Signup and view all the answers

How can a periodic wave be identified?

<p>By cycles or patterns produced repeatedly. (B)</p> Signup and view all the answers

If a wave travels with a velocity of $3 × 10^8 m/s$ and has a frequency of $1230 × 10^3 Hz$, what is its wavelength?

<p>$0.243 m$ (A)</p> Signup and view all the answers

What does the period of a wave represent?

<p>The time taken for one complete cycle. (D)</p> Signup and view all the answers

Which type of wave is characterized by disturbances traveling along the same direction as the wave itself?

<p>Longitudinal wave (C)</p> Signup and view all the answers

What is the relationship between sound intensity and distance from the sound source?

<p>Intensity is inversely proportional to the square of the distance. (B)</p> Signup and view all the answers

What is the speed of sound in air at 20 °C?

<p>330 m/s (A)</p> Signup and view all the answers

What is the threshold of hearing in watts per square meter?

<p>10^-12 W/m2 (C)</p> Signup and view all the answers

How do large visible ears help animals in detecting low-intensity sounds?

<p>They help to funnel sound waves toward the inner ear. (B)</p> Signup and view all the answers

If the sound intensity for listener 2 is 0.10 W/m2 at a distance of 640 m, what will the intensity be for listener 1 at 160 m?

<p>1.00 W/m2 (D)</p> Signup and view all the answers

What unit is used for measuring sound intensity?

<p>Watts per square meter (A)</p> Signup and view all the answers

Which of the following sound intensities is considered the threshold of pain?

<p>10^-4 W/m2 (C)</p> Signup and view all the answers

What happens to the sound pressure variations due to sound waves?

<p>They are superimposed on the ambient air pressure. (B)</p> Signup and view all the answers

Flashcards

Wave

A traveling disturbance that carries energy.

Transverse Wave

A wave where the disturbance is perpendicular to the direction of travel.

Longitudinal Wave

A wave where the disturbance is parallel to the direction of travel.

Wave Amplitude

The maximum displacement of a particle from its undisturbed position.

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Wavelength

The distance between two successive equivalent points on a wave (like two crests).

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Wave Period

The time it takes for one complete wave cycle to pass a point.

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Wave Frequency

The number of wave cycles per second.

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Wave Speed

The relationship between wavelength and frequency (v = fλ).

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Sound's nature

Sound is a longitudinal mechanical wave created by vibrating objects. It requires a medium (gas, liquid, or solid) to travel.

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Sound wave cycle

A sound wave's cycle includes a condensation (high pressure) and a rarefaction (low pressure).

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Pure tone

A sound wave with a single frequency is known as a pure tone.

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Frequency and Pitch

The human ear perceives the frequency of a sound wave as pitch. Higher frequency corresponds to higher pitch.

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Infrasonic

Sounds with frequencies below 20 Hz are called infrasonic.

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Ultrasonic

Sounds with frequencies above 20 kHz are called ultrasonic.

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Pressure Amplitude and Loudness

The pressure amplitude of a sound wave determines its loudness. Larger amplitude means louder sound.

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Sound Speed Change

The speed of sound changes when it travels from one medium to another, but its frequency remains constant.

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Speed of Sound

The speed at which sound waves travel through a medium, determined by the properties of the medium itself. In air at 20°C, it's approximately 330 m/s, while in water, it's about 1400 m/s.

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Sound Intensity

The amount of sound power passing through a unit area perpendicular to the direction of sound propagation. Measured in watts per square meter (W/m²).

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Inverse Square Law

The intensity of sound decreases proportionally to the square of the distance from the source, assuming uniform radiation in all directions and no reflections.

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Threshold of Hearing

The minimum sound intensity detectable by the human ear, approximately 10⁻¹² W/m² at 3000 Hz.

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Threshold of Pain

The maximum sound intensity that the human ear can tolerate without discomfort, approximately 10⁻⁴ W/m². Sound levels exceeding this can cause ear damage.

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Large Ears for Better Hearing

Animals with large ears have increased sensitivity to low-intensity sounds because the larger surface area captures more sound energy.

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Why does listener 2 hear a quieter sound?

Listener 2 is farther away from the source of sound compared to listener 1. According to the inverse square law, sound intensity decreases with distance, resulting in a quieter sound for listener 2.

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Why does the sound intensity decrease with distance?

Sound waves spread out as they travel from a source. This spreading causes the same amount of sound energy to be distributed over a larger area, resulting in a lower intensity at greater distances.

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Study Notes

Waves and Sound

  • A wave is a traveling disturbance that carries energy from place to place.
  • Waves are classified into transverse and longitudinal waves.

Transverse Wave

  • In a transverse wave, the disturbance is perpendicular to the direction of wave travel.
  • S waves are an example of transverse waves.

Longitudinal Wave

  • In a longitudinal wave, the disturbance is parallel to the line along which the wave travels.
  • P waves are an example of longitudinal waves.

Periodic Wave

  • A periodic wave consists of repeating cycles or patterns.
  • Wavelength (λ) is the distance between successive equivalent points (e.g., crests).
  • Period (T) is the time taken for one complete cycle.

Parameters Concerning Waves

  • Amplitude is the maximum displacement of a particle from its undisturbed position.
  • Wavelength is the distance between two successive equivalent points on the wave.
  • Period is the time required for one complete wavelength to pass a given point.

Frequency and Speed

  • Frequency (f) is the number of wave cycles per second (Hz).
  • Frequency is the reciprocal of period (f = 1/T).
  • Speed (v) of a wave is related to its wavelength and frequency (v = fλ).

Example (AM and FM Radio Waves)

  • AM and FM radio waves are transverse waves.
  • Radio waves travel at 3 × 10⁸ m/s.
  • Example calculations are given to determine wavelength from known frequency and speed.

The Mathematical Description of Waves

  • The displacement (y) of a particle at position x for a wave moving in the +x direction is given by: y = A sin(2πft - 2πx/λ).
  • For a wave moving in the -x direction, the equation is: y = A sin(2πft + 2πx/λ).

Example (Transverse Periodic Wave)

  • A problem concerning a transverse periodic wave and its characteristics is provided.
  • Students need to determine which statement about the wave is false.

Example (Wave Equation)

  • Another problem concerning a wave equation for a wave traveling in the +x direction is given.
  • Students need to choose the correct equation that describes the wave.

Check Your Understanding (Sound Wave in Air and Water)

  • A loudspeaker produces a sound wave that travels from air into water.
  • The frequency of sound remains the same as the source determines the frequency.
  • Speed of sound in air is 343 m/s; in water, it is 1482 m/s.
  • When the wave enters the water, the wavelength increases.

The Nature of Sound

  • Sound is a longitudinal wave; it is created by vibrating objects such as guitar strings or vocal cords.
  • Sound waves travel through a medium (solids, liquids, or gases).
  • Each sound wave cycle has a compression and rarefaction.

Check Your Understanding (Animal's Hearing)

  • Some animals have large ears for greater sensitivity detecting low-intensity sounds.

Check Your Understanding (Sound Intensity on a Surface)

  • A sound source emits sound uniformly in all directions.
  • Flat surface points facing the source face the same sound intensity.

Problems (Wave Equation)

  • Problems concerning wave equations, frequency, wavelength, and speed are provided.

Example (Sound Intensity)

  • Intensity problem related to a scenario in which a certain amount of sound power passes through labelled surfaces.
  • Sound intensity = power divided by area. SI unit is watts per square meter (W/m²).

Problems (Sound Intensity and Energy)

  • Problems relating sound intensity, energy, area, and time.
  • Sound intensity at each surface and how loud the sound is perceived by different listeners is examined

Solving for Sound Intensity (Inverse Square Law)

  • Problem related to determining sound intensity or power by using the inverse square law.

Sound Intensities and Human Hearing

  • The ear responds to a wide range of intensities.
  • The threshold of hearing is 10⁻¹² W/m².
  • The threshold of pain is 10⁻⁴ W/m².
  • High intensities can cause damage to the eardrum.

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Related Documents

Waves and Sound 1 Lecture Notes PDF

Description

Explore the key concepts of waves and sound through this quiz. Learn about the classifications of waves, including transverse and longitudinal, and delve into parameters such as amplitude, wavelength, and period. Test your understanding of these fundamental physics concepts.

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